Abstract: In order to achieve single lateral mode of the semiconductor laser, the methad was proposed to filter high-order lateral modes by introducing photonic crystal structures on both sides of ridge semiconductor laser. By adjusting the etching depth of the laser on the surface of the laser, and ridge width and spacing of photonic crystal region,the mode field distribution inside the laser was changed, combined with selective carrier injection to enhance the fundamental mode lasing advantage, thereby the numbers of the lateral mode were reduced. 1 550 nm wavelength semiconductor lasers were produced experimentally, and the width of the main ridge was 6 m, and the period of photonic crystal region was 5 m. Test results show that when the current was 300 mA in CW, the higher-order lateral modes were suppressed, and divergence angle was reduced to 10.2. It is confirmed that it is feasible to modulate lateral modes of semiconductor laser by photonic crystal structures.